Riex has a population () of 290. Over the last 10 years (1999–2009 ) the population has changed at a rate of 3.6%. It has changed at a rate of -2.1% due to migration and at a rate of 5% due to births and deaths. Most of the population () speaks
French (259 or 86.3%), with
German being second most common (21 or 7.0%) and
Portuguese being third (7 or 2.3%). There are 2 people who speak
Italian. , there were 103 people who were single and never married in the municipality. There were 160 married individuals, 21 widows or widowers and 16 individuals who are divorced. the average number of residents per living room was 0.54 which is fewer people per room than the cantonal average of 0.61 per room. About 53.1% of the total households were owner occupied, or in other words did not pay rent (though they may have a
mortgage or a
rent-to-own agreement). , there were 140 private households in the municipality, and an average of 2.1 persons per household. there were 151 apartments in the municipality. The most common apartment size was 3 rooms of which there were 46. There were 11 single room apartments and 35 apartments with five or more rooms. Of these apartments, a total of 128 apartments (84.8% of the total) were permanently occupied, while 21 apartments (13.9%) were seasonally occupied and 2 apartments (1.3%) were empty. Colors= id:lightgrey value:gray(0.9) id:darkgrey value:gray(0.8) ImageSize = width:1140 height:210 PlotArea = height:150 left:100 bottom:50 right:100 AlignBars = justify DateFormat = x.y Period = from:0 till:400 TimeAxis = orientation:vertical AlignBars = justify ScaleMajor = gridcolor:darkgrey increment:80 start:0 ScaleMinor = gridcolor:lightgrey increment:16 start:0 PlotData= color:yellowgreen width:40 mark:(line,white) align:center bar:1550 from:start till:84 bar:1550 at:94 fontsize:S text: "
21 Hearths" shift:(8,5) bar:1764 from:start till:294 text:"294" bar:1798 from:start till:351 text:"351" bar:1850 from:start till:368 text:"368" bar:1860 from:start till:353 text:"353" bar:1870 from:start till:397 text:"397" bar:1880 from:start till:353 text:"353" bar:1888 from:start till:365 text:"365" bar:1900 from:start till:349 text:"349" bar:1910 from:start till:287 text:"287" bar:1920 from:start till:273 text:"273" bar:1930 from:start till:310 text:"310" bar:1941 from:start till:276 text:"276" bar:1950 from:start till:291 text:"291" bar:1960 from:start till:291 text:"291" bar:1970 from:start till:289 text:"289" bar:1980 from:start till:293 text:"293" bar:1990 from:start till:282 text:"282" bar:2000 from:start till:300 text:"300" ==Heritage sites of national significance==